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PubMed1999

Wheat bran affects the site of fermentation of resistant starch and luminal indexes related to colon cancer risk: a study in pigs.

BACKGROUND: Recent studies suggest that resistant starch (effective in producing butyrate and lowering possibly toxic ammonia) is rapidly fermented in the proximal colon; the distal colon especially would, however, benefit from these properties of resistant starch. AIMS: To determine whether wheat bran (a rich source of insoluble non-starch polysaccharides), known to hasten gastrointestinal transit, could carry resistant starch through to the distal colon and thus shift its site of fermentation. METHODS: Twenty four pigs were fed four human type diets: a control diet, or control diet supplemented with resistant starch, wheat bran, or both. Intestinal contents and faeces were collected after two weeks. RESULTS: Without wheat bran, resistant starch was rapidly fermented in the caecum and proximal colon. Supplementation with wheat bran inhibited the caecal fermentation of resistant starch, resulting in an almost twofold increase (from 12.9 (2.5) to 20.5 (2.1) g/day, p<0.05) in resistant starch being fermented between the proximal colon and faeces. This resulted in higher butyrate (133%, p<0.05) and lower ammonia (81%, p<0.05) concentrations in the distal colonic regions. CONCLUSIONS: Wheat bran can shift the fermentation of resistant starch further distally, thereby improving the luminal conditions in the distal colonic regions where tumours most commonly occur. Therefore, the combined consumption of resistant starch and insoluble non-starch polysaccharides may contribute to the dietary modulation of colon cancer risk.

Ammonia↗
PubMed1992

Relationship of low lysine and high arginine concentrations to efficient ethanolic fermentation of wheat mash.

Very high gravity wheat mashes containing 20 or more grams of carbohydrates per 100 mL were fermented completely by Saccharomyces cerevisiae, even though these mashes contained low amounts of assimilable nitrogen. Supplementation of wheat mashes with various amino acids or with yeast extract, urea, or ammonium sulfate reduced the fermentation time. However, lysine or glycine added as single supplements, inhibited yeast growth and fermentation. With lysine, yeast growth was severely inhibited, and a loss of cell viability as high as 80% was seen. Partial or complete reversal of lysine-induced inhibition was achieved by the addition of a number of nitrogen sources. All nitrogen sources that relieved lysine-induced inhibition of yeast growth also promoted uptake of lysine and restored cell viability to the level observed in the control. They also increased the rate of fermentation. Experiments with minimal media showed that for lysine to be inhibitory to yeast growth, assimilable nitrogen in the medium must be in growth-limiting concentrations or totally absent. In the presence of excess nitrogen, lysine stimulated yeast growth and fermentation. Results indicate that supplementing wheat mash with other nitrogen sources increases the rate of fermentation not only by providing extra nitrogen but also by reducing or eliminating the inhibitory effect of lysine on yeast growth.

Arginine↗
PubMed1998

Traditional fermentation increases goitrogenic activity in pearl millet.

Epidemiological evidence suggests that millet might play a role in the etiology of endemic goiter. Recently, we showed that a traditional fermentation procedure of two pearl millet (Pennisetum americanum L. Lecke) cultivars grown in Sudan modified their effects on the weight of the thyroid gland and thyroid hormone profile in rats. In the present study, we report that this fermentation procedure reduced the ash contents of millet by about 40% and removed considerable amounts of Mg (>50%), Zn (27-39%) and K (45%). Other minerals (Ca, Fe, Cu) were not affected. Feeding of one fermented cultivar resulted in significant reduction in bone Mg and Zn contents, whereas feeding of the other fermented cultivar resulted in reduction of bone Mg only. Dietary Mg intake and bone Mg contents correlated negatively with serum T3. Groups fed the millet diets had higher serum Se level compared to those fed wheat or casein diets and feeding of fermented millet resulted in a further increase in serum Se level. Thus our data indicate that in rats the enhanced effects of millet on the thyroid induced by fermentation is likely related to removal of minerals from millet and/or chemical transformation of the goitrogens contained in millet.

Animals↗
PubMed2004

Sucrose fermentation by Saccharomyces cerevisiae lacking hexose transport.

Sucrose is the major carbon source used by Saccharomyces cerevisiae during production of baker's yeast, fuel ethanol and several distilled beverages. It is generally accepted that sucrose fermentation proceeds through extracellular hydrolysis of the sugar, mediated by the periplasmic invertase, producing glucose and fructose that are transported into the cells and metabolized. In the present work we analyzed the contribution to sucrose fermentation of a poorly characterized pathway of sucrose utilization by S. cerevisiae cells, the active transport of the sugar through the plasma membrane and its intracellular hydrolysis. A yeast strain that lacks the major hexose transporters (hxt1-hxt7 and gal2) is incapable of growing on or fermenting glucose or fructose. Our results show that this hxt-null strain is still able to ferment sucrose due to direct uptake of the sugar into the cells. Deletion of the AGT1 gene, which encodes a high-affinity sucrose-H(+) symporter, rendered cells incapable of sucrose fermentation. Since sucrose is not an inducer of the permease, expression of the AGT1 must be constitutive in order to allow growth of the hxt-null strain on sucrose. The molecular characterization of active sucrose transport and fermentation by S. cerevisiae cells opens new opportunities to optimize yeasts for sugarcane-based industrial processes.

Biological Transport↗
PubMed2025

Consumption of traditional Sardinian fermented milk promotes changes in the rat gut microbiota composition and functions.

BACKGROUND: Fermented milk products are part of the staple diet for many Mediterranean populations. Most of these traditional foods are enriched with lactobacilli and other lactic acid bacteria, as well as with metabolites resulting from lactose fermentation. Currently, there is very little scientific knowledge on how dietary supplementation with fermented milk affects the composition of the gut microbiota and its metabolic activities. RESULTS: We integrated 16&#xa0;S rRNA gene-based taxonomic profiling with metaproteomics-based functional analysis to investigate gut microbiota changes in rats exposed to an 8-week dietary supplementation with casu axedu, a traditional fermented milk produced within rural communities in Sardinia (Italy). Several microbial taxa showed a significantly increased abundance at the end of the dietary treatment, including Phascolarctobacterium, Prevotella, Blautia glucerasea, and Lactococcus lactis, while Bacteroides dorei and Helicobacter rodentium were decreased compared to the control rats. Metaproteomic analysis highlighted a striking reshaping of the Prevotella proteome in agreement with its blooming in casu axedu-fed animals, suggesting an increase of the glycolytic activity through the Embden-Meyerhof-Parnas pathway over the Entner-Doudoroff pathway. Moreover, an increased production of enzymes involved in succinate biosynthesis was observed, which in turn significantly boosted the abundance of Phascolarctobacterium and its production of propionate. Fermented milk consumption also promoted microbial synthesis of branched chain essential amino acids L-valine and L-leucine. Finally, metaproteomic data indicated a reduction of bacterial virulence factors and host inflammatory markers, suggesting that the consumption of casu axedu can have beneficial effects on the gut mucosa health. CONCLUSIONS: Our integrated multi-omics approach reveals that dietary supplementation with the traditional Sardinian fermented milk, casu axedu, induces significant shifts in the rat gut microbiota composition and function, characterized by the enrichment of beneficial taxa and metabolic pathways associated with improved gut health and reduced inflammation.

Animals↗
PubMed2005

Effects of fermentation products of pro- and prebiotics on trans-epithelial electrical resistance in an in vitro model of the colon.

Evidence from in vivo and in vitro studies suggests that the consumption of pro- and prebiotics may inhibit colon carcinogenesis; however, the mechanisms involved have, thus far, proved elusive. There are some indications from animal studies that the effects are being exerted during the promotion stage of carcinogenesis. One feature of the promotion stage of colorectal cancer is the disruption of tight junctions, leading to a loss of integrity across the intestinal barrier. We have used the Caco-2 human adenocarcinoma cell line as a model for the intestinal epithelia. Trans-epithelial electrical resistance measurements indicate Caco-2 monolayer integrity, and we recorded changes to this integrity following exposure to the fermentation products of selected probiotics and prebiotics, in the form of nondigestible oligosaccharides (NDOs). Our results indicate that NDOs themselves exert varying, but generally minor, effects upon the strength of the tight junctions, whereas the fermentation products of probiotics and NDOs tend to raise tight junction integrity above that of the controls. This effect was bacterial species and oligosaccharide specific. Bifidobacterium Bb 12 was particularly effective, as were the fermentation products of Raftiline and Raftilose. We further investigated the ability of Raftilose fermentations to protect against the negative effects of deoxycholic acid (DCA) upon tight junction integrity. We found protection to be species dependent and dependent upon the presence of the fermentation products in the media at the same time as or after exposure to the DCA. Results suggest that the Raftilose fermentation products may prevent disruption of the intestinal epithelial barrier function during damage by tumor promoters.

Anticarcinogenic Agents↗
PubMed2006

Effects of water-soluble carbohydrate content on silage fermentation of wheat straw.

To determine a suitable initial water-soluble carbohydrate (WSC) content to make wheat straw natural fermentation successful and to study fermentation characteristics, glucose was used to adjust the initial WSC content to 1.4%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, and 10.0% dry matter (DM) in the wheat straw. At 30 d of fermentation, there were three pHs: when the initial WSC content was 1.4%, the pH was 5.5; when the initial WSC contents were 4.0%, 5.0% and 6.0%, the pHs were near 5.1; and when the initial WSC contents were 7.0%, 8.0%, 9.0% and 10.0%, the pHs were near 4.0. The pattern of changes in WSC content during the fermentation was similar to that in pH. At 30 d of fermentation, there existed a dividing line in WSC remnants between the initial 6.0% WSC treatment and the initial 7.0% WSC treatment. When the initial WSC content was more than 7.0%, the remaining WSC content was more than 23.7 g/kg DM. When the initial WSC content was less than 6.0%, the remaining WSC content was less than 13.6 g/kg DM. Particularly for the 1.4% WSC treatment, the remaining WSC content was 2.1 g/kg DM. The results of the microbiological enumeration showed that with the increase in initial WSC content, the numbers of lactic acid bacteria (LAB) and other bacteria generally decreased. Denaturing gradient gel electrophoresis (DGGE) results showed that when the initial WSC content was beyond 7.0%, the LAB of the fermentation system were detected.

Biotechnology↗
PubMed2006

High-cell-density fermentation for ergosterol production by Saccharomyces cerevisiae.

The direct feedback control of glucose using an on-line ethanol concentration monitor for ergosterol production by high-cell-density fermentation was investigated and the fermentation parameters (e.g., pH, dissolved oxygen, ethanol concentration, oxygen uptake rate, carbon dioxide evolution rate and respiratory quotient) were analyzed. Controlling glucose feeding rate in accordance with ethanol concentration and adjusting pH with ammonia during the fermentation process were effective fed-batch methods for ergosterol production. The fermentation parameters well described the variation of the whole fermentation process. Cultivation in a 5 l fermentor was carried out under the following conditions: culture temperature, 30 degrees C; pH, 5.5; agitation speed, 600 rpm; fermentation time, 60 h; controlling ethanol concentration below 1% and keeping respiratory quotient (RQ) at approximately 1.0. Under these conditions, the yeast dry weight reached 120 g/l and the ergosterol yield reached 1500 mg/l.

Bioreactors↗
PubMedDate not supplied

Invertase production on solid-state fermentation by Aspergillus niger strains improved by parasexual recombination.

Invertase production by Aspergillus niger grown by solid-state fermentation was found to be higher than by conventional submerged fermentation. The haploid mutant strains Aw96-3 and Aw96-4 showed better productivity of various enzymes, as compared to wild-type parental strain A. niger C28B25. Here we use parasexual crosses of those mutants to increase further the productivity of invertase in solid-state fermentation. We isolated both a diploid (DAR2) and an autodiploid (AD96-4) strain, which were able to grow in minimal medium after mutation complementation of previously isolated haploid auxotrophic strains. Invertase production was measured in solid-state fermentation cultures, using polyurethane foam as an inert support for fungal growth. Water activity value (Aw) was adjusted to 0.96, since low Aw values are characteristic in some solid-state fermentation processes. Such diploid strains showed invertase productivity levels 5-18 times higher than levels achieved by the corresponding haploid strains. For instance, values for C28B25, Aw96-3, Aw96-4, DAR2, and AD96-4 were 441, 254, 62, 1324, and 2677 IU/(L x h), respectively. These results showed that genetic recombination, achieved through parasexual crosses in A. niger, results in improved strains with potential applications for solid-state fermentation processes.

Aspergillus niger↗
PubMed2005

Fermentability of water-soluble portion to ethanol obtained by supercritical water treatment of lignocellulosics.

The water-soluble (WS) portion obtained by supercritical water treatment of lignocellulosics was studied for its fermentability to ethanol. A fermentation test of the WS portion showed it was not fermented to ethanol. Therefore, a wood charcoal treatment was applied to the WS portion to remove furan and phenolic compounds, which are thought to be the inhibitors to sugar fermentability. It was found that treatment with wood charcoal can be effective at removing these inhibitors and improving the fermentability of the WS portion without reducing the levels of fermentable sugars.

Cedrus↗
PubMed2006

Lactic acid fermentation in cell-recycle membrane bioreactor.

Traditional lactic acid fermentation suffers from low productivity and low product purity. Cell-recycle fermentation has become one of the methods to obtain high cell density, which results in higher productivity. Lactic acid fermentation was investigated in a cell-recycle membrane bioreactor at higher substrate concentrations of 100 and 120 g/dm3. A maximum cell density of 145 g/dm3 and a maximum productivity of 34 g/(dm3.h) were achieved in cell-recycle fermentation. In spite of complete consumption of substrate, there was a continuous increase in cell density in cell-recycle fermentation. Control of cell density in cell-recycle fermentation was attempted by cell bleeding and reduction in yeast extract concentration.

Biomass↗
PubMed2000

Repeated solid-phase fermentation and extraction for enzyme production.

Solid-phase fermentation has been found to have a much higher productivity than the popular liquid submerged fermentation in producing cellulase enzymes. The highest reported productivity in the literature for cellulases by Trichoderma cultures in submerged fermentation is 158 filter paper units (FPU)/(h.L) of fermenting liquid. From preliminary experiments of solid-phase fermentation in 1000-mL flasks, a productivity of 234 FPU of cellulases/(h.L) of solid-bed volume was obtained. When two novel techniques--pressure pulsation and repeated extraction--were applied, a productivity of 806 FPU/(h.L) was achieved. The same techniques also greatly enhanced the productivity of other enzymes by fungal cultures in solid-phase fermentation.

Biotechnology↗
PubMed2001

Fermentation of xylose into acetic acid by Clostridium thermoaceticum.

For optimum fermentation, fermenting xylose into acetic acid by Clostridium thermoaceticum (ATCC 49707) requires adaptation of the strain to xylose medium. Exposed to a mixture of glucose and xylose, it preferentially consumes xylose over glucose. The initial concentration of xylose in the medium affects the final concentration and the yield of acetic acid. Batch fermentation of 20 g/L of xylose with 5 g/L of yeast extract as the nitrogen source results in a maximum acetate concentration of 15.2 g/L and yield of 0.76 g of acid/g of xylose. Corn steep liquor (CLS) is a good substitute for yeast extract and results in similar fermentation profiles. The organism consumes fructose, xylose, and glucose from a mixture of sugars in batch fermentation. Arabinose, mannose, and galactose are consumed only slightly. This organism loses viability on fed-batch operation, even with supplementation of all the required nutrients. In fed-batch fermentation with CSL supplementation, D-xylulose (an intermediate in the xylose metabolic pathway) accumulates in large quantities.

Acetic Acid↗
PubMed1995

Preventing in vitro lactate accumulation in ruminal fermentations by inoculation with Megasphaera elsdenii.

In vitro fermentations containing a mixed culture of ruminal bacteria (ruminal fluid from a hay-fed steer), buffer, and primarily rapidly degradable substrates (starch, glucose, cellulose, cellobiose, and trypticase) were inoculated with an overnight culture of Megasphaera elsdenii B159. Triplicate flasks were either uninoculated or inoculated to obtain a final concentration of 8.7 x 10(5) and 8.7 x 10(6) colony forming units of M. elsdenii per milliliter of culture fluid. Inoculation with M. elsdenii prevented an accumulation of lactic acid and excessive drop in pH. Lactate peaked at more than 40 mM in untreated cultures. In cultures inoculated with a low dose of M. elsdenii, lactate concentration peaked at approximately 25 mM at 5 h of fermentation but decreased rapidly to less than 5 mM by 7 h of fermentation. With the addition of the high dose of M. elsdenii, lactate was never greater than 2 mM (P < .05) throughout fermentation. Cultures treated with M. elsdenii had greater amounts (P < .05) of isobutyrate, butyrate, isovalerate, and valerate than untreated cultures. After 24 h of fermentation, one-half of the culture fluid was transferred to an equal volume of fresh buffer with substrate but was not inoculated with further quantities of M. elsdenii. Six hours after transfer, cultures that had been originally treated with M. elsdenii had lower (P < .05) amounts of lactate than untreated cultures. Inoculation with M. elsdenii has potential to prevent lactate accumulation in diets containing readily fermentable carbohydrates.

Animals↗
PubMed1995

Dietary fiber for cats: in vitro fermentation of selected fiber sources by cat fecal inoculum and in vivo utilization of diets containing selected fiber sources and their blends.

Two experiments were conducted to evaluate the addition of single sources and blends of dietary fibers to cat diets. In Exp. 1, fermentability of selected fibrous substrates by cat fecal microflora was evaluated. After 24 h of fermentation, OM disappearance (OMD) and total short-chain fatty acid (SCFA) production were greatest (P < .05) for citrus pectin, guar gum, and locust bean gum, whereas Solka Floc resulted in the least (P < .05) OMD and total SCFA production. In Exp. 2, six diets were formulated based on results of Exp. 1. The highest (P < .05) digestibilities of DM and OM occurred when cats consumed the diet with no supplemental fiber, and the lowest (P < .05) digestibilities occurred when cats consumed the SCFA blend (SC) diet. Nitrogen and lipid digestibilities also were lowest (P < .05) for cats consuming the SC diet, whereas total dietary fiber (TDF) digestibility (P < .05) was greatest for cats consuming the beet pulp, SC, and combination blend diets. Fecal consistency scores were highest (P < .05) for cats consuming the SC diet, indicating liquid, unformed stools. In conclusion, the in vitro fermentation technique was reasonably accurate in predicting in vivo digestion of fiber. The SC diet, which contained the most fermentable fibers, severely decreased nutrient digestibility and resulted in poor stool characteristics. Diets that contain moderately fermentable fiber provide fermentation end products that may be important in maintaining the health of the gastrointestinal tract of the cat.

Animal Feed↗
PubMed2002

Effects of dietary protein and fermentable fiber on nitrogen excretion patterns and plasma urea in grower pigs.

Effects of dietary protein concentration (high, 18.5; low, 15.7%) and fermentable fiber (control; soyhulls, SH; and sugar beet pulp, SBP) on N excretion patterns and plasma urea were tested in a 2 x 3 factorial arrangement. The objectives were: 1) to determine if reduced dietary protein together with fermentable fiber would reduce urinary N excretion further than a single diet manipulation, 2) to determine if effects of diet manipulations were similar between pigs with restricted and free access of feed, and 3) to further develop predictions of urinary N excretion using plasma urea. Diets were formulated to 3.30 Mcal digestible energy (DE)/kg and 2.4 g of digestible lysine per Mcal DE, and supplemented with lysine, methionine, tryptophan, threonine, isoleucine, leucine, or valine to ensure meeting an ideal AA profile. Pigs (30.5 +/- 3 kg; n = 36) were housed in metabolism crates with restricted access to feed (3 x 110 kcal DE/kg BW(0.75)) from d 1 to 18, and free access from d 19 to 26. Feces and urine were collected from d 15 to 18 and d 23 to 26, and blood was sampled on d 17 and 25. With restricted access to feed, urinary N was reduced 28% and N retention was reduced 12% for the low- compared to high-protein diet (P < 0.01; as g/d). Fecal N was increased 4% units for SH and 6.5% units for SBP (P < 0.01; as % of N intake) and urinary N was reduced 5% units for SH (P < 0.10) and 9% units for SBP (P < 0.05) compared to the control. With free access to feed, urinary N was reduced 27% (P < 0.05; as g/d) and N retention was reduced 7% (P < 0.10) for the low- compared to high-protein diet. Fecal N was increased 5% units for SH and 9% units for SBP (P < 0.001; as % of N intake), and urinary N was reduced 9% units for SH and 10% units for SBP (P < 0.01) compared to the control. For either restricted or free access to feed, fermentable fiber did not affect N retention (P > 0.10). A protein x fiber interaction was not observed for urinary N excretion (P > 0.10), indicating that reducing dietary protein and including fermentable fiber reduced urinary N excretion in an additive manner. Daily urinary N excretion was related positively and linearly with plasma urea in pigs with free access to feed (R2 = 0.71; at 0800). In summary, reduction of dietary protein reduced urine N excretion, and fermentable fiber shifted N excretion from urine to feces. Effects of dietary protein and fermentable fiber on reducing urinary N excretion are additive.

Animals↗
PubMed2003

Fermented and nonfermented liquid feed to growing pigs: effect on aspects of gastrointestinal ecology and growth performance.

The effect of feeding dry feed (DF), nonfermented liquid feed (NFLF), and fermented liquid feed (FLF) to growing pigs on aspects of gastrointestinal ecology and on performance was investigated. Nonfermented liquid feed was prepared by mixing feed and water at a ratio of 1:2.5 immediately before feeding. Fermented liquid feed was prepared by mixing feed and water in the same ratio as NFLF, and stored in a tank at 20 degrees C for 4 d, after which half the volume was removed twice daily at each feeding and replaced with the same volume of feed and water mixture. A total of 60 pigs (initial BW of 30.7 kg) from 20 litters was used. Twenty pigs, housed individually, were allotted to each of the diets and fed restrictively. Five pigs from each diet were sacrificed at an average BW of 112 kg and digesta from the gastrointestinal tract (GI-tract) was obtained to examine variables describing some aspects of the gastrointestinal ecology. Fermented liquid feed contained high levels of lactic acid bacteria (9.4 log cfu/g) and lactic acid (approximately 169 mmol/kg), low levels of enterobacteria (<3.2 log cfu/g), and had a low pH (4.4). Nonfermented liquid feed contained 7.2 log cfu/g of lactic acid bacteria, and 6.2 log cfu/g of enterobacteria, which indicated that fermentation had started in the feed. The pigs fed FLF had the lowest levels of enterobacteria along the GI-tract (<3.2 to 5.0 log cfu/g), and those fed NFLF the highest levels (5.7 to 6.6 log cfu/g; P < or = 0.02). Fermented liquid feed caused a decrease in gastric pH from 4.4 and 4.6 for DF and NLF, to 4.0 (P = 0.003), and increased numerically the gastric concentration of lactic acid (P = 0.17) from 50 to 60 mmol/kg in the DF and NFLF treatments to 113 mmol/kg in the FLF treatment. The animals fed NFLF showed the highest weight gain (995 g/d) and feed intake (2.14 kg/d), and those fed FLF the lowest values (weight gain, 931 g/d; feed intake, 1.96 kg/d; P = 0.003 for weight gain, and P < 0.001 for feed intake). The results from the present study indicate that feeding FLF as prepared here may be a valid feeding strategy to decrease the levels of enterobacteria in the GI-tract of growing pigs, whereas feeding liquid feed that has started to ferment (high levels of enterobacteria and high pH as with NFLF) increases the presence of these undesirable bacteria. Nonetheless, higher daily feed intake and body weight gain are obtained when feeding NFLF compared with feeding FLF or DF.

Animal Feed↗
PubMed2004

Effects of natural plant extracts on ruminal protein degradation and fermentation profiles in continuous culture.

Eight dual-flow continuous culture fermenters were used in four consecutive periods of 10 d to study the effects of six natural plant extracts on ruminal protein degradation and fermentation profiles. Fermenters were fed a diet with a 52:48 forage:concentrate ratio (DM basis). Treatments were no extract (CTR), 15 mg/kg DM of a mixture of equal proportions of all extracts (MIX), and 7.5 mg/kg DM of extracts of garlic (GAR), cinnamon (CIN), yucca (YUC), anise (ANI), oregano (ORE), or pepper (PEP). During the adaptation period (d 1 through 8), samples for ammonia N and VFA concentrations were taken 2 h after feeding. On d 9 and 10, samples for VFA (2 h after feeding), and peptide, AA, and ammonia N concentrations (0, 2, 4, 6, and 8 h after feeding) were also taken. Differences were declared at P < 0.05. During the adaptation period, total VFA and ammonia N concentrations were not affected by treatments. The acetate proportion was higher from d 2 to 6 in CIN, GAR, ANI, and ORE, and the propionate proportion was lower from d 2 to 4 in CIN and GAR, and from d 2 to 5 in ANI and ORE, compared with CTR. However, the proportion of individual VFA (mol/100 mol) was similar in all treatments after d 6, except for valerate in d 9 and 10, which was lower in PEP (2.8 +/- 0.27) compared with CTR (3.5 +/- 0.27). The average peptide N concentration was 31% higher in MIX, and 26% higher in CIN and YUC compared with CTR (6.5 +/- 1.07 mg/100 mL). The average AA N concentration was 17 and 15% higher in GAR and ANI, respectively, compared with CTR (7.2 +/- 0.77 mg/100 mL). The average ammonia N concentration was 31% higher in ANI and 25.5% lower in GAR compared with CTR (5.5 +/- 0.51 mg/100 mL). The accumulation of AA and ammonia N in ANI suggested that peptidolysis and deamination were stimulated. The accumulation of AA N and the decrease in ammonia N in GAR suggests that deamination was inhibited. The accumulation of peptide N and the numerical decrease in AA N in CIN suggest that peptidolysis was inhibited. Results indicate that plant extracts modified ruminal fermentation, but microbes were adapted to some extracts after 6 d of fermentation. Therefore, data from short-term in vitro fermentation studies may lead to erroneous conclusions, and should be interpreted with caution. Careful selection of these additives may allow the manipulation of protein degradation in the rumen.

Acetates↗